I've just tried it out and is pretty awesome. Mosh is an ssh clients for being used in mobile device with high latency link or that uses roaming (such as 3G networks an so). Mosh is for mobile-shell.
The main feature, apart from the roaming (thing that you can achieve with autossh, too), is the preemptive local echo. I'll explain what's that in a second.
With the default ssh client, when you press a key on your keyboard a TCP segment is sent to the server saying "key T has been pressed". Then you have the response back saying "OK, that's cool". Then bash (on the server side) prints the T key in the pseudo-terminal. It has to notify back to the client, so SSH sends a package to you saying "Hey, a T has appeared on the pseudo-terminal, you should print that", and the client response is something like "cool! I got it!". That's a 4 TCP segments going back and forward. In a 223ms ping link, that's a lot time waiting just for a character you have pressed to appear on your screen.
So, the MIT guys thought that they could improve that process by assuming that the character that you have already pressed on your local machine is the one that will appear on the screen next. They check if that assumption was right anyways, but you have a much more sense of speed because you actually see the character on your screen even before it has been received by the server.
The thing is that they use SSH protocol for authenticating and everything and they use UDP for synchronizing the state of any object from one host to another. This is a downside, since you must open ports from 60000 to 61000 (UDP) in your firewall (server-side). But not everything could be perfect!
So, if you are working with your servers and changing the location all the time, mosh or autossh are your friends. If you just have a connection with a lot of ping (latency) or jitter, give mosh a try!
Of course, you can use your packet manager in your distribution for installing the tool. You must install it in both client and server side! And remember the firewall stuff, too! People says that have a terminal with a permanent connection to they Linode host and that mosh works great (I don't know why you want to be always connected, by the way...)
Take care, Jan